EIT IEW a a Got ES 
= er 5 
i 
i | DETRITIC FORMATIONS 81 
almost exclusively brown sandstone with small outcrops of an un- 
derlying red sandstone at the foot of the ridge. The brown layers 
lie in quite an undisturbed position in this profile, but soon they 
incline to the west, as shown in the transverse quebradas. 
The river gorge between the Jaguel bolson and Vinchina (Rio 
Jaguel) reveals, going westward, the following profile: 
_ The brown sandstone layers, outcropping in the bluff at Vinchina 
in an almost horizontal position with red layers at the base, dip, 
as stated, westward with gradually increasing gradient. Simultane- 
- ously the chocolate-brown colour of the rock changes into a pale 
brown one, but of similar lithological character as the former. 
Further to the west, the consistence of the rock, however, becomes 
softer. The dip then attains its maximum (about 45° W) and re- 
mains so in the rest of the profile (see further on). 
_ This apparently quite uniform sedimentary series is overlaid with 
a mighty mass of surely younger strata of much softer consistence. 
_ These lie in conformity over the older, but are separated from them 
by a slight conglomeratic layer. The younger strata are of some 
different colours, pale salmon-red, or pale brownish, and often carry 
interstratifications of conglomeratic layers, attaining sometimes a 
considerable thickness. The consistence of the strata generally 
changes towards the west to greater softness. The dipping angle 
is always the same, 45° W. No doubt the soft series belong to 
young geological horizons (cretaceous-lower tertiary?), while the 
underlying sandstones are of the upper „Paganzo“ series. South 
off the described profile the soft strata are with strong unconformity 
overlapped by a young conglomerate (late tertiary?), described on 
pages 113—115. Also to the north the same overlap can be observed, 
as it seems, on a much greater scale.! | 
The westward dipping strata of the zone disappear swiftly under 
the modern accumulations of the Jaguel bolson. 
1 This observation was made only by field-glass. 
